Webster defines asterism as an optical phenomenon of some crystals - TopicsExpress



          

Webster defines asterism as an optical phenomenon of some crystals that exhibit a star-shaped body produced by reflected light or by transmitted light and gives star sapphire and mica as examples Asteria, or star stone (from Gr. star) is a name applied to ornamental stones that exhibit a luminous star when cut en cabochon. The typical asteria is the star-sapphire, generally a bluish-grey corundum, milky or opalescent, with a star of six rays. In red corundum the stellate reflection is less common, and hence the star-ruby occasionally found with the star-sapphire in Ceylon is among the most valued of fancy stones.
Posted on: Mon, 15 Sep 2014 00:57:11 +0000

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